The Alethinophidia are an infraorder of snakes that includes all snakes other than blind snakes and thread snakes. Snakes have long been grouped into families within Alethinophidia based on their morphology, especially that of their teeth. More modern phylogenetic hypotheses using genetic data[2][3][4][5][6][7][8][9][10][11][excessive citations] support the recognition of 19 extant families (see below), although the taxonomy of alethinophidian snakes has long been debated, and ultimately the decision whether to assign a particular clade to a particular Linnaean rank (such as a superfamily, family, or subfamily) is arbitrary.
^Scanlon, J. D.; Lee, M. S. Y. (2011). Aldridge, R. D.; Sever, D. M. (eds.). The Major Clades of Living Snakes: Morphological Evolution, Molecular Phylogeny, and Divergence Dates in Reproductive Biology and Phylogeny of Snakes. Enfield, NH: Science Publishers. pp. 55–95.
^Vidal, N.; Delmas, A. S.; Hedges, S. B. (2007). Henderson, R. W.; Powell, R. (eds.). The higher-level relationships of alethinophidian snakes inferred from seven nuclear and mitochondrial genes. Eagle Mountain, Utah, USA: Eagle Mountain Publishing. pp. 27–33.
^Vitt, L. J.; Caldwell, J. P. (2014). Herpetology: an introductory biology of amphibians and reptiles (4th ed.). Burlington: Academic Press. pp. 108–109.